White's tree frog (Litoria caerulea), also known as the Australian green tree frog, simply green tree frog in Australia, or dumpy tree frog, is a species of arboreal toad native to Australia and New Guinea. It has introduced populations in New Zealand, South America, and Florida. White's tree frog is almost indistinguishable from the magnificent tree frog, Litoria splendida, and similar to the white-lipped tree frog (Litoria infrafrenata).
White's tree frog is larger than most Australian frogs, reaching 10 centimetres (4 inches) in length. The average lifespan of the frog in captivity, about sixteen years, is long in comparison with most frogs. Green Tree Frogs are docile and well suited to living near human dwellings. They are often found on windows or inside houses, eating insects drawn by the light.
Due to its physical and behavioural traits, White's tree frog has become one of the most recognisable frogs in its region, and is a popular exotic pet throughout the world. The skin secretions of the frog have antibacterial and antiviral properties that may prove useful in pharmaceutical preparations.
White's tree frog shares the Litoria genus with dozens of frog species endemic to Australasia. The common name of the species, "White's tree frog", is in honour of John White's first description in 1790. White's tree frog was the first Australian frog scientifically classified; the specimen found its way into the collection of Sir Joseph Banks, but was destroyed with the German bombing of the Hunterian Museum at the Royal College of Surgeons in London in World War II.
The species was originally called the "blue frog" (Rana caerulea) despite its green colour. The original specimens White sent to England were of a mutant moph and coloured a light sky blue. The colour of the frog is caused by blue and green pigments covered in a yellow layer; the mutant frogs lacked yellow pigment on their bodies and thus appeared blue. The specific epithet, caerulea, which is Latin for blue, has remained.
Physical description Edit
White's tree frog can grow up to 10 centimetres (4 inches) in length. Its color depends on the temperature and colour of the environment, ranging from brown to green; the ventral surface is white. The frog occasionally has small, white, irregularly shaped spots on its back, up to five millimetres in diameter, which increase in number with age. The frog has large discs at the end of its toes, of about five millimetres in diameter at maturity. These help the frogs grip while climbing and allow them to climb vertically on glass. The eyes are golden and have horizontal irises, typical of the Litoria genus. The fingers are about one-third webbed, and the toes nearly three-quarters webbed. The tympanum (a skin membrane similar to an eardrum) is visible.
White's tree frog appears similar to the Magnificent tree frog (Litoria splendida), which inhabits only north-western Australia and can be distinguished by the presence of large parotoids and rostral glands on the head. The white-lipped tree frog (Litoria infrafrenata) is also sometimes confused with White's tree frog. The main difference is a distinct white stripe along the edge of the lower jaw of L. infrafrenata, which is not present in White's tree frog.
White’s tree frogs are very docile. They are nocturnal and come out in early evenings to call (in spring and summer) and hunt for food. During the day they find cool, dark, and moist areas to sleep such as tree holes or rock crevices. In the winter, White’s tree frogs do not call and are not usually seen.
Depending on their location, White’s tree frogs occupy various habitats. Typically, they are found in the canopy of trees near a still-water source. However, they can survive in swamps (among the reeds) or in grasslands in cooler climates. White’s tree frogs are well known for inhabiting water sources inside houses, such as sinks or toilets. They can also be found on windows eating insects. They will occupy tanks (cisterns), downpipes (downspouts), and gutters, as these have a high humidity and are usually cooler than the external environment. The frogs are drawn to downpipes and tanks during mating season, as the fixtures amplify their call.
The species' call is a low, slow Brawk-Brawk-Brawk, repeated many times. For most of the year, they call from high positions, such as trees and gutters. During mating season the frogs descend, although remaining slightly elevated, and call close to still-water sources, whether temporary or permanent. Like many frogs, White’s tree frogs call not only to attract a mate. They have been observed calling to advertise their location outside the mating season, usually after rain, for reasons that are uncertain to researchers. They will emit a stress call whenever they are in danger, such as when predators are close or when a person steps on a log in which a frog resides.
The species' diet consists mainly of insects and spiders, but can include smaller frogs and even small mammals. Frog teeth are not suited to cutting up prey, so the prey must fit inside the mouth of the frog. Many frogs propel their sticky tongues at prey. The prey sticks, and is consumed. A White’s tree frog will use this technique for smaller prey; however for larger prey, it pounces, then forces the prey into its mouth with its hands.
The frog has a few native predators, among them snakes and a few species of lizards and birds. Since the European settlement of Australia, non-native predators have been introduced, primarily dogs and cats. The species has an average life expectancy in captivity of sixteen years, but some have been known to live for over twenty years, which is long for a frog. The average life expectancy in the wild is lower than in captivity, due to predation.
ReproductionEditLike many tree frogs, White's tree frogs breed during the rainy season in the summer. Males reach sexual maturity slightly earlier than females, and develop a functional vocal sac several months prior to maturity. They also arrive at breeding sites before females, their distinctive croaking call sounding much like a door slowly opening. Breeding takes place in streams, shallow ponds, puddles formed by rain, and even in storm drains.
Amplexus in L. caerulea is axillary (the males embracing the females around their armpits). Males release clouds of sperm into the water, and the females then forcefully expel their eggs in clumps. The eggs drift through the cloud of sperm and, as they are fertilized, sink to the bottom of the stream, puddle or pond and hatch after approximately three days of development.